One piece or unitary child-resistant vial containers have been utilized for quite some time. Compared to two piece child-resistant containers, which typically involve a push and turn or squeeze and turn function to open, one piece child-resistant containers typically involve a simpler squeeze to open mechanism. These vials are child resistant because their construction gives them a squeeze resistance that children simply don't have the grip strength to open.
One piece child-resistant vial containers are often referred to as “pop-tops”, based on the sound they make when being opened due to the pressure and force resistance of the vial container.
Current one piece child resistant vial containers have a flat lid. Some lids have text on top, but the profile of these container lids are all relatively flat.
These vial containers are typically manufactured via injection molding and offer both an economic and functional advantage over traditional two piece child-resistant containers.
Due to limitations in plastic injection molding technology, it is much more expensive to manufacture a unitary child-resistant vial container in with a lid that has an intentional or specific color difference than the body of the container.